We found the flat very conveniently placed: the airport bus stops very near, there are 2 MAS supermarkets within walking distance ( Carlos V and Menendez Pelayo), and the historic centre is 10 minutes walk away.
The flat is well furnished , clean and easy to live in. The kitchen is rather small and we did miss not having a dishwasher.
We did have problems with the electricity: the power cut out very easily, for instance if a heater and toaster were on together. There are instructions about what to do if this happens, and the owners were helpful. Be sure you know what to do if this happens.
We were there in January and found the heating insufficient. It would be fine later in the year.
Altogether we enjoyed our stay and would recommend the flat with the above provisos.